fix(windows): click in 1 pixel high box in Language Switch window caused crash

Fixes #7698.

Due to a `>` instead of a `>=` check, there was a one pixel high box at
the bottom of each list of input methods for each language which would
reuslt in an invalid value for `FNewHoverKeyboard`
(`lang.KeyboardCount`).

As well as fixing this, I changed the result for clicking below the
input method list to the more logical last item in the list rather than
the first.